package com.sun.showcase.utils;

import java.math.BigDecimal;
/**
 * double类型精度问题
 *
 */
public class ArithUtil {
	private static final int DEF_DIV_SCALE = 2;

	private ArithUtil() {
	}
	/**
	 * 加法
	 * @param d1
	 * @param d2
	 * @return
	 */
	public static double add(double d1, double d2) {
		BigDecimal b1 = new BigDecimal(Double.toString(d1));
		BigDecimal b2 = new BigDecimal(Double.toString(d2));
		return b1.add(b2).doubleValue();

	}
	/**
	 * -法
	 * @param d1
	 * @param d2
	 * @return
	 */
	public static double sub(double d1, double d2) {
		BigDecimal b1 = new BigDecimal(Double.toString(d1));
		BigDecimal b2 = new BigDecimal(Double.toString(d2));
		return b1.subtract(b2).doubleValue();

	}
	/**
	 * -法
	 * @param d1
	 * @param d2
	 * @return
	 */
	public static double sub(double d1, double d2, int scale,int roundMode) {
		BigDecimal b1 = new BigDecimal(Double.toString(d1));
		BigDecimal b2 = new BigDecimal(Double.toString(d2));
		return b1.subtract(b2).setScale(scale, roundMode).doubleValue();

	}
	/**
	 * x法
	 * @param d1
	 * @param d2
	 * @return
	 */
	public static double mul(double d1, double d2) {
		BigDecimal b1 = new BigDecimal(Double.toString(d1));
		BigDecimal b2 = new BigDecimal(Double.toString(d2));
		return b1.multiply(b2).setScale(2, BigDecimal.ROUND_HALF_UP).doubleValue();

	}
	/**
	 * ÷法
	 * @param d1
	 * @param d2
	 * @return
	 */
	public static double div(double d1, double d2) {

		return div(d1, d2, DEF_DIV_SCALE);

	}

	public static double div(double d1, double d2, int scale) {
		if (scale < 0) {
			throw new IllegalArgumentException(
					"The scale must be a positive integer or zero");
		}
		BigDecimal b1 = new BigDecimal(Double.toString(d1));
		BigDecimal b2 = new BigDecimal(Double.toString(d2));
		return b1.divide(b2, scale, BigDecimal.ROUND_HALF_UP).doubleValue();

	}
	
	public static double div(double d1, double d2, int scale,int roundMode) {
		if (scale < 0) {
			throw new IllegalArgumentException(
					"The scale must be a positive integer or zero");
		}
		BigDecimal b1 = new BigDecimal(Double.toString(d1));
		BigDecimal b2 = new BigDecimal(Double.toString(d2));
		return b1.divide(b2, scale, roundMode).doubleValue();

	}
}
